dDAC design schematics showing body and piezoelectric (PE) actuators. (a) Cross-sectional view showing cylindrical body above the plate with locations of PE actuators and static load screw anvils. (b) End-on view showing positioning of pe actuators, static load screws, and guide pins.
Schematic of dDAC operation showing instrumentation and connections including a shutter for time-resolved experiments.
Plot showing the dDAC pressure variation range at a given nominal pressure. The data are shown for a water sample ( diameter, diamond flats). The slope of this curve will increase for stiffer (less compressible) materials.
Time-resolved synchronization scheme for selectively probing the loading/unloading cycle of a sample in the dDAC. The time delay is selected by the digital delay/pulse generator and set to probe the desired range in the cycle. The drive wave form can be set as desired (ramp, step function, or pulse) provided it is within the performance range of the PE actuators. A sinusoidal drive is shown.
Time-resolved ruby fluorescence spectra of a sample in the dDAC. The sample (water, stainless steel gasket, thick) is being driven by a sinusoidal wave form with a period of . (a) The raw ruby spectra (exposure time ). The gray background strip emphasizes the movement of the ruby R1 fluorescence line. (b) The pressure as a function of time. Square symbols are the pressure determined from the ruby specta. Lines between the squares are a guide to the eye, emphasizing the abrupt jump at 18 and , and the dashed line is the voltage applied to the PE actuator. The pressure shows a smooth variation between 0.15 and , except for the kink in the rising edge, representative of the liquid-solid phase transition. Plateaus at 5 and are representative of melting.
Time-resolved Raman spectra of a nitrogen sample in the dDAC showing the transition from the phase to the phase. The pressure and elapsed time are written above the corresponding spectrum. The initial spectrum shows the pure phase Raman signal, coexistence at , and pure phase at . Spectra were collected using a trapezoidal drive wave form and a compression rate of . The measurement exposure window was and the signal averaged for .
Raman spectra of water supercompressed at a rate of in the dDAC. Metastable ice-VII at was formed from supercompressed water. Both the supercompressed water and the resultant ice-VII are within the thermodynamic stability field of ice-VI.
Video images in transmission of ice-VI crystals grown in the dDAC. Diameter of sample hole is . (a) A faceted well-formed ice-VI crystal produced at strain rate of . (b) a dendritic crystal formed at a strain rate of .
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